1. Field of the Invention
The present invention relates in general to a wireless network system constituted by an access point and a plurality of wireless devices, and these wireless devices, and more particularly to techniques that permit the wireless devices to easily join the wireless network system.
2. Description of Related Art
There have been proposed wireless networks using an electromagnetic wave as a physical medium, in place of conventional networks using cables or wires. A wireless LAN (Local area Network) designed according to IEEE802.11 standards is an example of the wireless LAN. JP-2003-338821 A discloses an example of a technique for interconnecting a plurality of wireless devices for radio communication with each other in such a wireless network.
The wireless LAN has two different communication modes called “ad hoc mode” in which the wireless devices are operated to communicate with each other, and “infrastructure mode” in which the wireless devices are not operated for direct communication with each other, but are operated for communication with each other through the access point which governs the wires LAN.
The wireless LAN described above is usually set up such that the wireless LAN is constituted by only intended wireless devices and access point, to prevent connection of the intended wireless devices to unintended wireless devices and access point, or to prevent the unintended wireless devices and access point from joining the wireless LAN. Such a setup of the wireless LAN must be performed in both the access point and the wireless devices. Where the wireless LAN includes a large number of intended wireless devices, the setup is cumbersome and time-consuming.
To solve the problem indicated above, Wi-Fi Alliance proposed a WPS [Wi-Fi (registered trademark) Protected Setup] method for easy setup of the wireless LAN. Wireless devices according to the WPS method are commercially available. An example of the WPS method is disclosed in “BUFFALO Wireless LAN broadband router WZR-AMPG144NH” retrieved on line on Mar. 1, 2007 from the Internet: URL:http://buffalo.jp/products/catalog/network/wzr-ampg144nh/”. In this WPS method, the task required to setup the access point and wireless devices of the wireless LAN is reduced by automatic generation of SSID (Service Set Identifier) which is the name of the network constituted by the access point and wireless devices, and WPA2 which is the security key for encryption communication between the access point and the wireless devices, as disclosed in “Wi-Fi Alliance, Wi-Fi CERTIFIED for Wi-Fi Protected Setup: Easing the User Experience for Home and Small Office Wi-Fi Networks, [online], Wi-Fi Alliance, 2007, retrieved on 2007-03-01 from the Internet: URL:http://www.wifialliance.com/files/wp.sub.—18.sub.—20070108_Wi-Fi_Protected_Setup_WP_FINAL.pdf”.
For setting up the wireless LAN according to the WPS method, there are available a Push Button Configuration (PBC) approach and a PIN (Personal Information Number) code approach. According to the Push Button Configuration approach, users pushes buttons provided on the access point and wireless devices, for mutual communication of information for setting up the wireless LAN and storing identifiers of the wireless devices in a registrar (which is a selected one of the wireless devices), so that the wireless devices are automatically enabled to communicate with the access point. According to the PIN code approach, on the other hand, a PIN code (eight-digit number, for example) as an identifier which identifies each wireless device is registered in the registrar, so that the wireless devices are automatically enabled to communicate with the access point.